AUDI A4 QUATRO. I WAS ONLY PERSON IN THE CAR. SLOWING TO A STOP WAS HIT FROM THE REAR @ 55MPH BY A FORD TRUCK F550. TRUCK #4 SLAMMED INTO MY REAR CAR #3 WHICH SLAMMED INTO CAR #2 & FINALLY CAR #1. *AK MY TRUNK ENDED UP IN MY BACK SEAT, MY FRONT LOOKED LIKE AN ACORDIAN. THOUGH I AM ALIVE. MY DRIVER AIRBAG & DRIVER CURTAIN DID NOT DEPLOY!! MY SEAT BELT DID NOT HOLD ME BACK. THE FORCE WAS SO GREAT THAT I BROKE THE REAR VIEW MIRROR WITH MY HEAD AND I CONTINUED INTO THE WINDSHIELD. I HAVE SEVERE CONCUSION, CAN NOT WORK & OF COURSE HAVE A WONDERFUL CASE OF WHIPLASH! AUDI CONSUMER IS TRYING TO TELL US THAT THE "PASSANGER" AIR BAG WENT OFF BECAUSE THE SEATBELT WAS NOT CLOSED! HOW STUPID! I THOUGHT BEING HIT @ THAT SPEED WITH SUCH A FORCE TO CREATE A CHAIN REACTION INTO THREE CARS..THE AIRBAGS SHOULD HAVE DEPLOYED & THE DRIVER SEATBELT SHOULD HAVE PREVENTED ME FROM HITTING MY STERNUM ON THE STEERING WHEEL. WHICH, BY THE WAY WAS BENT BY MY BODY! ON THE FORCE OF MY CAR HITTING THE CAR IN FRONT OF ME...I BROKE MY SEAT & WAS IN A PRONE POSITION WHEN THE FIREDEPARTMENT CAME TO CUT ME OUT OF MY CAR. CAN YOU PLEASE ADVISE @ WHAT SPEED AN AIRBAG SHOULD DEPLOY! SHOULD THEY NOT DEPLOY WITH BACK HIT, AS WELL AS, A FRONT HIT? EVEN THOUGH I WAS SLOWING TO 5MPH, I HAD AMPLE ROOM BETWEEN MY CAR & THE CAR IN FRONT OF ME. I WWAS HIT @55MPH AND THE FORD F550 DID NOT EVEN BRAKE OR ATTEMPT TO STOP. THUS MY SPEEN BECAME MORE THAN 5MPH.